Revision 2 of the hardware resolved a number of power and layout issues from revision 1. The hardware can now both charge the battery over USB and run directly off of it. There are also pads to attach a power switch. The below image shows the new PCB with the battery ziptied down. The toggle switch and corresponding wires are visible.
The firmware works on these prototypes. The only game built so far lights up one target randomly and fades down to off. If impact is detected before the fade is complete, the impacted target responds to the main target with the amount of time it took. Sadly I am not able to test them in a realistic scenario right now, but the gif below shows them operating.